One reason is that it could just be clogged with dust and dirt that has accumulated around the fan. This will stop the fan from functioning effectively. There is an easy fix for this and that is to give the fan a thorough cleaning, then, periodically check for dirt and give the fan a clean to ensure it continues to work well.
There are some houses where the fans connecting duct work doesn’t actually vent all the way out to the home’s exterior, but instead, only goes as far as the attic space. You might not find this is a problem for your bathroom, but it is a problem for your attic. Excess moisture being vented into your attic can cause all kinds of issues like mold and the decaying of the attic’s materials. If you are concerned about this, you might want to have it inspected.
While you might hear the fan turn on and think it is working, what are some other signs that it is not functioning correctly? Look out for corroding of bathroom fixtures, also you might notice paint starting to bubble and peel due to an excess of moisture. Does there seem to be an excessive amount of moisture on walls and ceilings?
If you have noticed any of these signs and feel concerned that your bathroom fan is not working correctly, please feel free to contact us and we will be happy to advise you.